Using bluetooth for Pandora in carGeneral

I did a search and it looks like some others had problems with this as well. I am new to the Droid world (tried Blackberry but hated it) and I really like the phone overall, minus a few software bugs. Anyway, my question is how do I set up the phone to play in the car? I have bluetooth on my car and it works for phone calls (it drops every now and then) but I can't get the audio to work. My bluetooth manual for my Volkswagon says the phone needs to be turned onto headset mode? How do I do this and are there any other suggestions to try?

I also have a Aux hookup and an Ipod connection. However, I really wanted to use the bluetooth if possible. I haven't tried the Aux hook up yet either.